This invention relates to a gas/liquid mixing device for keeping a gas such as air or ozone for a long time in liquid such as water as innumerable atomized bubbles by mixing and dissolving it in water.
When a gas such as oxygen or ozone is mixed and dissolved in water, water is activated by oxygen, the water quality improves, and polluted water is purified. Ozone water in which ozone is dissolved is usable for sterilization, deodorization, and keeping freshness. Thus various trials have been made to dissolve these gases at high concentrations. To dissolve such gases, heretofore, an arrangement in which gas is atomized and mixed using an injection nozzle is mainly used.
As an example of a device for dissolving oxygen in water, a bubble generator disclosed by unexamined Japanese patent publication 4-126542 is known. This bubble generator has a cylindrical body having one end closed and the other end open, an opening for introducing liquid into the cylindrical body in a tangential direction, and an opening at the closed end for introducing gas at the central position of the cylindrical body. Into the mixing chamber defined in the cylindrical body, liquid flows in a swirling state to draw gas from the opening for drawing external air under the suction force produced near the center of the flow of liquid. Colliding hard against the liquid flow, the gas turns into microscopic bubbles and is mixed in the flow of liquid.
As an example of an air mixing device for producing ozone water, a gas contact device and an ozone water generator are known from unexamined Japanese patent publication 5-123554. An ejector type nozzle which is a main part of this device has a liquid nozzle at the center. Through a suction gas chamber provided therearound, gas is drawn under negative pressure due to discharged flow of liquid, and discharged as bubbles through a gas discharge hole formed in a gas nozzle member (cap) at the tip of the nozzle.
When oxygen or ozone gas is dissolved in water, using the above-described nozzle type gas/liquid mixing device, they try to form bubbles having as small a diameter as possible and mix them in water to dissolve gas in the water. But with the nozzle type, forming bubbles having such a diameter that they are visible to the eye is the limit. Since such bubbles are large in buoyancy, even when mixed in water, they soon float up and disappear, so that they cannot remain in water for a long time.
Especially when ozone water is produced by a gas/liquid mixing device, solubility of ozone varies markedly with temperatures. For example, compared with 10xc2x0 C. water, for 30xc2x0 C. water, it decreases markedly to half, and it decreases in summer, when people want to use ozone water for sterilization and deodorization. Ozone that does not dissolve in water is released into the atmosphere as waste ozone. When such waste ozone is released into the atmosphere in large amounts, it will have a negative influence on the work environment. Thus, in producing ozone water in such a conventional gas/liquid mixing device, a device for disposing of waste ozone, using e.g. using a catalyst is needed.
An object of this invention is to provide a gas/liquid mixing device in which bubbles having such a small diameter as to be invisible are produced and dissolved in water in a short time, whereby the solubility of gas can be improved greatly.
According to this invention, there is provided a gas/liquid mixing device comprising a mixing cylinder submerged in liquid for mixing liquid with gas, and a gas supply means for supplying gas into the mixing cylinder, a mixing/compressing means provided in the mixing cylinder for compressing a gas/liquid mixture, a driving unit coupled to the mixing/compressing means for driving it, the gas supply means having a gas supply port in the mixing cylinder, and a bubble dispersing area provided for a predetermined length and at a predetermined distance from the mixing/compressing means. The mixing cylinder is formed with a plurality of holes in its peripheral wall at the bubble dispersing area, whereby the gas is mixed in liquid in the form of bubbles, and the bubbles are sufficiently compressed and atomized by the mixing/compressing means and are discharged through the holes out of the mixing cylinder.
Other features and objects of the present invention will become apparent from the following description made with reference to the accompanying drawings, in which: